It has long been recognized that it would be highly desirable to have available Si-based lasers, LEDs or optical amplifiers, since availability of these devices would greatly ease the difficulty of integrating optical and electronic functions on a single chip. Furthermore, the high thermal conductivity of Si could result in operational advantages. However, up to now efforts to obtain Si-based LEDs, lasers or amplifiers, especially such devices that operate at commercially interesting wavelengths (e.g., about 1.3 or 1.5 .mu.m) have not been successful.
H. Ennen et al. [Applied Physics Letters, Vol. 43, page 943 (1983)] pointed out the potential of rare earth (RE) ions in a semiconductor matrix for the development of LED's and lasers. Erbium (Er) is a promising candidate because it shows luminescence in Si at about 1.54 .mu.m, a wavelength of interest for, inter alia, optical fiber communications. See, for instance, H. Ennen et al., Applied Physics Letters, Vol. 46, page 381 (1985). Recently it was observed that the presence of oxygen in Er-doped Si results in increased Er photoluminescence, [P. M. Favennec et al., Japanese Journal of Applied Physics, Vol. 29, page L524, (1990)]. In these studies Er was introduced into Si by implantation, either during MBE growth or in the as-grown substrate. Further background material can be found in U.S. patent application Ser. No. 07/579,118, filed Sept. 7, 1990 for G. E. Blonder et al., now U.S. Pat. No. 5,039,190, incorporated herein by reference.
However, despite intense effort and some resultant progress, the art has not yet succeeded in the quest for a Si-based RE-doped LED, laser or optical amplifier, at least in part due to the fact that the observed luminescence is too weak to support such a device. Thus, it would be of substantial interest to discover means for increasing the luminescence from RE-doped Si beyond what can be obtained by the incorporation of oxygen into the Si. This application discloses such means.